70 NEW YORK STATE MUSEUM 
The Mohawk and upper Hudson valleys have been so broadly 
and deeply trenched through soft strata that in them no remnants 
of the peneplain surface remain. Immediately eastward in the 
Berkshires, however, the old surface is well exhibited. In the 
Highlands-of-the-Hudson, a view from one of the high points 
shows a rather even sky line at an altitude of from 1200 to 1500 
feet, the somewhat lower elevation of the old surface here being 
due to the fact that this region was east of the main axis of uplift. 
Since the actual work of erosion or dissection of the upraised 
peneplain occurred during the Cenozoic era, further discussion of 
the subject is reserved for the next chapter. It has been the present 
purpose to prove that the Cretacic peneplain actually existed and 
that it was upraised. 
FAULTING OF DHE EASTERN ADTRONDAGKS 
The eastern and southern Adirondack regions have been exten- 
sively fractured or faulted (see figures 23 and 24). In fact the 
major topographic features of those regions such as the numerous 
north-northeast by south-southwest ridges and valleys are largely 
(ea a 
aN ioe 
Fic. 23 Cross-section of a normal Fic. 24 Cross-section of a reversed 
fault. or thrust fault. 
dependent upon this faulted siructure. These fractures are all of the 
normal fault type with fault surfaces practically vertical. Examina- 
tion of the topographic maps of the whole eastern and southern Adi- 
rondacks shows that by far most of the ridges and valleys, streams 
and lakes trend in a north-northeast by south-southwest direction, 
or perfectly parallel to the direction of the major faults. Up to 
the present, no single fault has been proved to extend across the 
entire region, but rather there is a series of numerous parallel faults, 
no one of which has been traced much over 20 or 30 miles. The 
exact amount of displacement along these lines of fracture in the 
ancient crystalline rocks can not be determined, but many times it 
amounts to at least 2000 feet. 
